1. Field of the Invention
The present invention relates to a sound absorption and noise reduction apparatus, and particularly to a sound absorption plate with a unit structure used for the interior of a building to eliminate a reverberant sound field.
2. Description of Related Art
In the modern city construction, requirements on indoor acoustic environments of large and medium-sized public buildings are getting higher and higher, and particularly for indoor decorative materials of large and medium-sized public buildings, both beautiful decorative features and excellent acoustic functions are required. However, conventional indoor decorative materials of large and medium-sized public buildings generally use aluminum strip-shaped, aluminum square-shaped or aluminum bracket-shaped ceilings and shingles and the like having micropores with a pore size of Φ 1-3 mm. Although these indoor decorative materials have certain sound absorption properties, actual sound absorption effects thereof are very poor, and cannot meet design requirements on indexes of indoor acoustic environment of modern large and medium-sized public buildings at all. In order to overcome defects of conventional ceilings and shingles, some modified ceiling and shingle products appear on the market currently, and sound absorption properties thereof are improved but still cannot reach satisfactory sound absorption effects.
Chinese patent application 201120333488.1 discloses “an ultramicropore sound absorber”. The sound absorber includes a front plate provided with ultramicropores, and the front plate is formed into a rectangular body. A sound absorption oblique sheet carrying ultramicropores is provided within the rectangular body, and sealing cover plates are disposed at two ends of the rectangular body. The sound absorption oblique sheet may be a V-shaped sound absorption wedge. The sealing cover plates may carry ultramicropores or may not carry ultramicropores as needed. The ultramicropore sound absorber facilitates improvement of sound absorption properties, but still has the following shortcomings: the adoption of the sound absorption oblique sheet or the V-shaped sound absorption wedge changes the structure of an inner cavity, and a graduated cavity formed by the oblique sheet makes a sound absorption frequency band wider to a great extent; however, since a total sound absorption area in respective frequency ranges is reduced and accordingly, a sound absorption coefficient in respective frequency ranges tends to decrease as a whole, an average sound absorption coefficient is not high.
Chinese patent application 201320835639.2 discloses “a metal ultramicropore sound absorption hanging piece”. The sound absorption hanging piece includes side plates and a support top plate, ultramicropores are disposed on the side plates, and the side plates and the support top plate define an inner cavity. A separator is disposed inside the inner cavity. Clamping edges are disposed on the side plates, and sealing cover plates are disposed at two ends of the inner cavity. The cross-sectional shape of the sound absorption hanging piece may be rectangular, semi-circular or wedge shaped. Different shapes of separators are disposed inside the cavity as needed, and sealing cover plates are disposed at two ends of the sound absorption hanging piece. The sound absorption hanging piece has better acoustic properties, but still has the following shortcomings: firstly, it is influenced by the product dimension, and has better sound absorption effect in middle and high frequencies and relatively poor sound absorption effect in a low frequency; and secondly, it has better sound absorption effect only in a specific range and has poor sound absorption effect in other frequency ranges, with a relatively narrower frequency band.
Chinese patent application 201410322266.8 discloses “a sound absorption plate”. The sound absorption plate includes a sound absorption front plate, a sealed-type cavity sound absorption back plate and side edges. A set of ultramicropores are disposed on the sound absorption front plate, and the sealed-type cavity sound absorption back plate and the sound absorption front plate are connected to define a sealed-type cavity. The side edges for installation are disposed at rims of the sound absorption front plate. The sound absorption plate can utilize sheet resonance sound absorption of the sealed-type cavity sound absorption back plate to achieve better sound absorption effect without adding any fibrous material, but still has the following shortcomings: firstly, a specific disadvantage still exist that a sound absorption frequency band of a single-layer sound absorption plate is relatively narrower, and better sound absorption effect cannot be achieved in all frequency ranges in a wide frequency band range; and secondly, although sheet resonance sound absorption of the sealed-type sound absorption back plate is utilized, it is found through analysis by reference to the sheet resonance sound absorption theory from an overall installation structure that a dimension behind the sealed cavity is relatively large, the action of sound pressure energy is difficult to cause resonance of the sheet, so that resonance sound absorption effect of the sheet will be relatively limited.
Chinese patent application 201210398343.9 discloses “an environmental-friendly sound absorption wall with a sandstone plastered structure”. The sound absorption wall is composed of seven layers and fixed on an original wall surface. A gas-permeable plate layer is disposed on a base layer, an epoxy resin adhesive layer is disposed on the gas-permeable plate layer, a cotton plate layer is disposed on the epoxy resin adhesive layer, a grid cloth layer is disposed on the cotton plate layer, a sandstone environmental-friendly sound absorption plate is disposed on the grid cloth layer, and a porous nano polymeric sand coating layer is disposed on the sandstone environmental-friendly sound absorption plate. The sandstone environmental-friendly sound absorption plate is plastered on the grid cloth after mixing 20-mesh to 100-mesh natural sands or natural color round sands with a bi-component water-soluble modified epoxy resin adhesive, with no seam in the entire wall surface; and then the porous nano polymeric sand coating layer is used to treat the wall surface, where the size of sands determines the number of pores, and different design schemes are adopted for different use sites. The sound absorption wall has better sound absorption effect than common walls, but still has the following shortcomings. Firstly, the porous nano polymeric sand coating layer is a particle coating formed by polymerizing nanoscale stone powder, having a particle size of 60 to 120 mesh (about 300-125 um), and since the sand dimension of the coating layer is large, a specific surface area of sand pores of the coating layer is small, thereby directly affecting improvement of the sound absorption effect. Secondly, although there are plenty of pores inside the particle coating layer, and the treated surface layer has a flow resistance value of 300 Pa·s/m-1000 Pa·s/m at a thickness of 2 mm and has good sound absorption effect, there still exist a deviation from a flow resistance value range reflecting the optimal sound absorption effect which is well-known in the art. Thirdly, since the sand dimension in the porous nano polymeric sand coating layer is large, the numbers of sands and pores both are small, thereby directly affecting absorption for high, middle and low sound frequencies. Fourthly, since there exists no sound absorption resonance cavity structure, it is difficult for sound energy to be effectively absorbed by the sound absorption wall surface, thereby directly affecting the sound absorption and noise reduction effect.
To sum up, how to overcome the shortcomings in the prior art has become one of the key problems to be solved in the art of sound absorption and noise reduction apparatuses.